View Compilation Error

0_0_3878076_15180.cpp: In function `int abscmp(const void*, const void*)':
0_0_3878076_15180.cpp:10: error: `abs' undeclared (first use this function)
0_0_3878076_15180.cpp:10: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_3878076_15180.cpp: In function `int main(int, char**)':
0_0_3878076_15180.cpp:25: error: `qsort' undeclared (first use this function)